Water-tube boiler



Jan. 31, 1928. 1,657,951

. H. E. YARROW WATER TUBE BOILER Filed y 15. 1925 tubes.

Patented Jan. 31, 1928.

PAT

V HAROLD EDGAR YAR-ROW, 0]? GLASGOW, SCOTLAND.

warnarunn Bonanza.

epplication filed May 15, 1925, Serial No. 3059?, and in Great Britain November 7,

This invention relates to water tube boilers fired by pulverized fuel. In such boilers a large combustion space is required for the combustion of the fuel and further, to keep the temperature of this combustion space sufficiently low to prevent rapid deterioration of the brickwork of the furnace, it necessary to have a large heat-absorbing surface exposed to the radiation from, the incandescent flame. Further, it is also nec essary or desirable that the incombustible portions of the powdered fuel should be reduced in temperature before it collects in the ashpit, as otherwise it is liable to form large lumps which are difficult to remove.

These conditions are secured according to the present invention by the specific arrangement of steam'and water drums and their connecting tubeshereinafter described. In this arrangement there is a single elevated steam drum and a pair of water drums at a lower level or lower levels, one on each side of the combustion chamber and connect ed with the steam drum by banks of water In addition there is another water drum at a still lower level substantially in the same vertical plane as the steam drum and connected by a bank or banks of tubes with both of the other two water drums. The combustion space 1s thus bounded upon all four sides by banks of water tubes which provide the necessary large heat-absorbing and radiating surface without materially re stricting the combustionspace which is very large compared with the total space occupied by the boiler. r

Ono ernl'iodiu'lent of the invention is illustra ted in the accompanying drawing which shows a cross section of a Yarrow boiler adapted for burning pulverized fuel.

In the drawing A is the elevated steam drum and B and C two water drums, one at either side of the furnace and either at the same level or, as shown, with one of the water drums, namely C, at a somewhat lower level than the other. In addition there is a central water drum D at a still lower level and substantially vertically below the steam drum A. The water drum B which is upon that side of the furnace leading to the up take for the furnace gases is preferably of greater diameter than either of the others and is connected with the steam drum A by a bank of water tubes E of considerable depth, the water drumC upon that side of be connected with only one of the other Water drums, for example water drum C, by water tubes.

The banks of tubes 1 G and if need only be of comparatively small depth, for

example three or four rows, as they are substantially subject to heating only by radiation from the combustion chamber and are not swept by the furnace gases on their passage to the uptake as in the case of the tubes l In this arrangement a large combu:= tion chamber I enclosed by water tubes is provided for the combustion of the pul verlzed fuel injected by fuel burners such J into the furna e, spaces being left in the bank F of water tubes for the accommodation of these burners. V

he lower banks of tubes G, H, besides constitutingadditional heat-absorbing and radiating surfaces, serve also to reduce the temperature of the incombust-ible elements of the fuel as it drops in a powdered form towards the ashpit-s K and L, and this incombustible material being thus cooled while in a finely divided state is thereby prevented from becoming consolidated and forming a fused mass "in the ashpits from which it can therefore be easily removed in the form of dust.

The furnace gases, after traversing the main bank of ater tubiiss lil, pass to a smolzebox M and thence thron -l an uptake N to the chimney direct or alter first pass ing through an economizer superheater or air heater, or any two or more of thcsede vices.

By arranging the water drum C at a lower level than thewater drum B and disposing the fuel burners J in one or more rows immediately above the water drum C, the burning fuel assumes a curved path through the burners J to the uptake which, throughout a large portion of its length, is substantially parallel with the tubes H and G, so that as the ash separates from the flame it falls through these banks of tubes into the ash spaces L, K. into which the burning gases lltl do not pass and which, being thus screened from the furnace, have a relatively low temperature. 7

As in other known constructions of Yarrow boilers the water drum B and bank of tubes E maybe replaced by two water drums each connected by a bank of. tubes with the steam druniA and a superheater intercalated between these two banks of; tubes.

The circulation of water in, all the banks of tubes is in accordance with the well known Yarrow system and it is not necessary to provide any special. means for circulating the water in the two lower banks of tubes because there will be a circulation initiated in these tubes between the lowest drum and one or both of the side water drums.

Having thus described the nature of the said invention and the best means I know of carrying the same into practical ehlect I claim 1. A. water tube boiler tl'or burning pulverized fuel comprising; four banks of water tubes arranged in lozenge or diamond form in a closed series of two upper and two lower banks, fuel jets directing streams of combustible transversely through one of the said upper banks of tubes in a direction substantially parallel with the tubes of: an adjacent lower bank, and a single uptake tor the combustion products, said, uptake being disposed on the side of the boiler opposite. to the said fuel jets.

2. A water tube boiler to: burning pul verized fuel comprising an elevated steam drum, two water drums parallel therewith but at a substantially lower level, one on either side of the ilurnacm a drum at a still lower level oi 1e l'urnaee and located sul .ztnntially dirwlh below the stean'i drum. four banks oi water tubes eonneeting the water drums in a closed series fuel jets directing streams olf eoiuluwtilile transversely through one of the upper baulw; of water tubes into the space enclosed by the saic. :liour banks of tubem and an uplulre for the waste gases located beyond the other of the upperbanlrs o'l 'ater tubes.

3. A, water tube boiler acem'dingr to claim 2, wherein one of the two llI'$-'t'-.llltl1l'l011ml water drums is at a lower water level than the water drum on the opposite side (it lll( furnace and toe pulverized 'liuel burners ar disposed immediately above the water drum. substantially as described.

In testimony whereof I have sinned my name to this specification.

HAROLD E. YiUlllOll third water tl 

